Exemplary embodiments of the present disclosure relate generally to hollow castings and, in one embodiment, to method of producing multi-passage hollow castings.
Many castings have hollow passages that are difficult to cast. In some cases, the difficulty can arise from passages being so small or narrow that an investment casting slurry cannot be effectively applied in multiple layers with intermittent drying to allow for sufficient strength to be developed to withstand fluid flow dynamics and hydrostatic pressures of poured molten metal. On the other hand, in aluminum casting, a very fluid mold material like gypsum can be poured into intricate passages to have sufficient strength to form a “solid mold” structure. Rather than sequentially dip this material with intermittent drying, this material is poured all at once with chemical activation to dry the material to form the “solid mold” around a master wax pattern that forms the component. Once the wax is removed, aluminum is poured into the mold to allow the aluminum to solidify. Once solidified, the solid mold material is mechanically removed.
It has been observed, however, that no such processes exist for iron, nickel, cobalt base or other high temperature castings. In these or other cases, separate ceramic cores must be made (if possible), inserted into the component wax (or other material) pattern during injection and then sent through conventional investment casting sequential dip layer processes. This significantly increases manufacture lead time and cost.